Pocket lighter with child resistance mechanism

ABSTRACT

Pocket lighter with a child resistance mechanism, of the type comprising a liquated gas reservoir, a combustion chamber, a valve connecting liquated gas reservoir to combustion chamber, a lever that activates valve, a flint, a toothed wheel mounted in rotation around an axis and which rubs against said flint and at least one thumb wheel coaxial with axis and integral with toothed wheel. Thumb wheel has on its periphery a plurality of radial projections alternated with seating areas with respect to which said radial projections project. There are between three and ten radial projections, and they are free from any contact with any other element of the lighter.

FIELD OF THE INVENTION

The invention is concerned with the field of pocket lighters that are specially designed to be difficult for young children, particularly those under the age of five, to operate.

More particularly, the invention relates to a pocket lighter with a child resistance mechanism, of the type known by the English term “press & roll”, in other words, the type comprising a liquated gas reservoir, a combustion chamber, a valve connecting said liquated gas reservoir to said combustion chamber, a lever activating said valve, a flint, a toothed wheel mounted in rotation around an axis and which rubs against said flint creating sparks in the direction of said combustion chamber, and at least one thumb wheel, coaxial with said axis and integral with said toothed wheel, suitable for being rotated by a user's finger.

STATE OF THE ART

Conventional lighters of this type can be activated easily by a young child. In order to prevent the risk that this implies, and in many cases, following the specific regulation that has been developed in various countries, lighter manufacturers have created various models with a special design intended to make it difficult for a child to light them, without making the lighting operation too complicated for a fully able person.

Various solutions are known for achieving this aim. Essentially, the known solutions can be classified into three groups.

A first group includes the solutions based on including additional mechanical elements that block the rotation of the toothed wheel. Document U.S. Pat. No. 4,717,335 describes a lighter in which the toothed wheel is provided with projections that form an end stop against a structural element of the lighter, so that once the thumb wheel has been activated in the appropriate direction for producing the spark, it can only be activated again in the same direction if, beforehand, it is rolled back in the opposite direction. Document US2002/0160328 proposes a similar solution, with the exception that the projections are provided on the thumb wheels. Document US2003/0031968 describes a similar solution, in that the projections on the thumb wheels do not form an end stop against a structural element of the lighter, instead they rubs against the latter therefore hindering the rotation action. These solutions have the drawback that they include a mechanical complication that makes lighter manufacturing more expensive and, usually, has a negative effect on the lighter's robustness.

A second group includes the solutions based on increasing the radial force that a user has to apply with the finger in order to apply the tangential force necessary to rotate the thumb wheels, thus overcoming the friction resistance with the flint. For example, in the solution proposed by document EP0804707, this is achieved because the thumb wheels are smooth, in other words they have a smooth surface on their periphery, whereby the friction coefficient is low. This solution has the advantage that it only requires modifying the design of the thumb wheels and allows the other parts of the lighter to be left intact. In other solutions, this effect is achieved by providing some additional elements that hinder, but do not prevent, the finger's radial access to the thumb wheels or to the toothed wheels. For example, this is the case of the lighters disclosed in documents U.S. Pat. No. 5,096,414 and U.S. Pat. No. 5,520,197. In document U.S. Pat. No. 5,096,414, the toothed wheel does not have any thumb wheels and it is sunk between two side walls so that the finger is obliged to rest on said side walls and only reaches the surface of the toothed wheel with the centre of the fingertip. In document U.S. Pat. No. 5,520,197, the lighter is provided with a flexible element that extends above the toothed wheel, so that in order to reach the thumb wheels with the finger, it is first of all necessary to sink said flexible element. This last solution suffers from the same drawback as that mentioned in relation to the first group: the flexible element is an added element that introduces a mechanical complication and affects the lighter's robustness. Moreover, the flexible element's resistance can deteriorate over time, thus reducing the lighter's lighting resistance.

A third group includes the solutions based on modifying the relative position of the thumb wheels with respect to the structural elements surrounding them, so that said thumb wheels only project in one small angled sector. The intended effect is that a user's finger can only access the thumb wheels in said small projecting section and therefore can only rotate the toothed wheel at a reduced rotation angle. Solutions of this type are described, for example, in documents WO2005/108868, US2003194669 and WO02065019. These solutions have the advantage that, most of them, do not require additional mechanical elements. However, they suffer from the drawback that in order to achieve sufficient child lighting resistance, the sector where the thumb wheels project from the structural elements must be very small and therefore it is too difficult for an adult to work the lighter.

EXPOSITION OF THE INVENTION

The purpose of the invention is to provide a lighter of the type indicated at the beginning, in which the lighting resistance effect is based mainly on limiting the rotation angle of the toothed wheel when the user activates the thumb wheels, but so that said limitation occurs noticeably when the lighter is handled by a child and not when it is used by an adult. Another aim of the invention is that the lighting resistance effect is obtained by modifying only the thumb wheels, without having to modify other elements of the lighter or introduce additional mechanical elements.

This purpose is achieved by means of a lighter of the type indicated at the beginning, characterised in that said thumb wheel has a plurality of radial projections on its periphery, leaving a seating area defined between each pair of said radial projections, with respect to which seating area said radial projections project in the radial direction, said radial projections being free from all contact with any other element of the lighter, the total number of said radial projections being less than or equal to ten and greater than or equal to three.

The applicant has run tests with various embodiments of the lighter according to the invention. As a result, the applicant has observed that when the lighter is handled by an adult, the adult performs the lighting action as if it were a conventional lighter, that is, by placing the thumb finger in the highest position so as to obtain the maximum rotation path. If the initial position of the thumb wheel is such that one of the seating areas is at the top, the finger sits firmly and comfortably in this seating area, between the two radial projections, and the user completes the rotation without any problem. If, on the other hand, there is a radial projection at the top, the to finger first sits on said projection and, at the same time as it begins the rotating movement, it tilts so as to finally sit in the seating area located immediately afterwards, and the rotation is completed without any problem. Therefore it is observed that the particular geometry of the thumb wheel according to the invention has virtually no limiting effect on the rotation angle when the lighter is activated by an adult, and therefore it does not significantly hinder the lighting process.

However, when the lighter is handled by a young child, particularly a child under five, it is observed that the child naturally performs a gesture that differs considerably from that which the child would perform with a conventional lighter. In fact, with a conventional lighter a child uses the index finger (and not the thumb finger like an adult does) and normally places the finger at the top of the thumb wheel. This initial finger position is optimum with respect to lighting possibilities, because it offers a maximum path of effective rotation, whereby the child manages to work the lighter relatively easily. On the other hand, when a child handles a lighter according to the invention, it understands the radial protuberances to be gripping points and spontaneously places the index finger on one of them, normally against the rear side thereof, in other words the side joining it to the following seating area. It is unlikely that the initial position of the thumb wheel is such that a radial projection is located right at the top, whereby mostly the initial position of the child's index finger is far from the optimum position. Consequently, the toothed wheel's rotation angle is reduced and the child cannot activate the lighter. But even when the thumb wheel is in an initial position where one of the radial projections is at the top, or near the top, the toothed wheel's effective rotation angle is also reduced. In fact, in this position the child also places its finger on the rear side of the radial projection in an attempt to obtain a gripping point, but the finger arranged in this way has a fairly open angle and therefore quickly looses the contact with the thumb wheel once rotation has begun. The effective rotation angle is therefore reduced and the child cannot work the lighter either.

To summarise, the principle of the invention is based on the fact that a young child spontaneously places its finger on one of the radial projections and therefore, the toothed wheel's effective rotation angle is reduced.

In a preferred embodiment of the invention, there are two thumb wheels, arranged on both sides of said toothed wheel. This arrangement, with the toothed wheel framed between two thumb wheels, corresponds to the arrangement of a conventional lighter, the thumb wheels having been replaced with wheels according to the invention, provided with radial projections. In this case, the lighter according to the invention has an even greater child lighting resistance. In fact, it has been observed that when the lighter according to the invention is handled by a young child, the child places its finger spontaneously on only one of the thumb wheels, on one of the radial projections as explained above, and does not try to place the finger in the centre between the two thumb wheels for gaining support simultaneously from both wheels and the central toothed wheel as occurs when using a conventional lighter. Also, preferably, in this embodiment the thumb wheels are arranged with their radial projections in phase. Consequently, it is easier for an adult to work the lighter, without modifying the child lighting resistance. In fact, an adult rests its finger on the two wheels at the same time and, thanks to the fact that the projections on the two thumb wheels are in phase, the finger is arranged in an identical position with respect to each thumb wheel, whereby it is more comfortable to activate the thumb wheels, whereas nevertheless, as explained, a child places its finger on only one of the thumb wheels.

In some advantageous embodiments of the invention, wherein an optimum operation of the basic principle is obtained, there are a total of six, five or four of said radial projections and they are distributed at regular intervals around a circumference centred in said axis.

Preferably, said radial projections form, at the end therefore furthest away from said axis, a surface which is convex in a plane that is orthogonal to said axis, with a radius of curvature less than the radius from said axis to said end of the radial projection. This geometry contributes even more to a young child placing its finger on the rear side of the radial projection, looking for an effective support.

Preferably, said seating areas form a surface which is concave in a plane that is orthogonal to said axis. Thanks to this geometry of the seating areas, it is more comfortable for an adult to handle the lighter, without affecting the child lighting resistance.

Advantageously, in order to obtain the optimum operation of the invention's basic principle, the radial distance between the point of one seating area nearest the axis and the point of one radial projection furthest away from the axis is greater or equal to four tenths of a millimetre, and more preferably it is greater or equal to seven tenths of a millimetre.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and characteristics of the invention are apparent from the following description wherein, with a non-limiting character, some preferable embodiments of the invention are described, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are rear and side views, respectively, of a first embodiment of the lighter according to the invention;

FIGS. 3 and 4 are views corresponding to FIGS. 1 and 2, in section;

FIG. 5 is an enlarged view of FIG. 4, showing the top part of the lighter;

FIG. 6 is a side view of one of the thumb wheels of the lighter in FIGS. 1 through 5, shown separately;

FIGS. 7, 8, 9, 10, 11, 12, 13 and 14 are similar views to FIG. 6, showing different embodiments of the thumb wheel.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

FIGS. 1 through 5 show a first preferred embodiment of the lighter according to the invention. The lighter is of the type known by the English term “press & roll”, in other words in which the lighter is lit by rotating a toothed wheel 5 that produces friction on a flint 4 and sends sparks towards a combustion chamber 2 where a valve 3, activated by a lever 8, releases gas from a liquated gas reservoir 1. Toothed wheel 5 is cylindrical and integral on both sides with two thumb wheels 7, which are coaxial with said toothed wheel 5 and which project in the radial direction with respect to the latter. The integral unit made up of toothed wheel 5 and the two thumb wheels 7 is mounted in rotation around an axis 6 on two side supports 12 forming part of the body of the lighter. In order to activate toothed wheel 5, an adult places its thumb finger on thumb wheels 7 and rotates them.

According to the invention, the lighter shown in FIGS. 1 through 5 is characterised by the particular shape of thumb wheels 7, which on its own gives the lighter child lighting resistance, as explained above. This particular shape of thumb wheels 7 consists in the periphery 9 thereof having a plurality of radial projections 10 free from any kind of contact with any element of the lighter. Between each pair of consecutive radial projections 10, a seating area 11 is defined with respect to which said radial projections 10 project in the radial direction. As can be seen particularly in the side views in FIGS. 5 and 6, in this preferred embodiment, thumb wheels 7 have a total of six, identical radial projections 10, arranged at regular intervals around a circumference centred on axis 6. Between them, said radial projections 10 define six seating areas 11, also identical to one another, with respect to which they project in the radial direction. Radial projections 10 have, at the end thereof furthest away from axis 6, a rounded shape made up of a surface which is convex in a plane that is orthogonal to axis 6. The radius of curvature of said convex surface is less than that of a circumference that is centred in axis 6 and passes through said end. Seating areas 11, for their part, in the plane of thumb wheel 7 have a surface which is concave in a plane that is orthogonal to axis 6, which, following a gentle transition, without any singularity, joins the convex surfaces of the adjacent projections 10. In this example, the radial distance between the point of one seating area 11 nearest axis 6 and the point of one radial projection 10 furthest away from axis 6 is 0.85 millimetres. The maximum radius of thumb wheel 7, in other words the radius centred on axis 6 and which passes through the end of a radial projection 10, is 4.45 millimetres.

FIGS. 7 through 14 show some of the possible variations of thumb wheel 7 which characterises the lighter according to the invention, whereby all of said variations can be mounted in the lighter illustrated in FIGS. 1 through 5 by replacing thumb wheel 7 shown in said figures.

FIG. 7 shows a thumb wheel 7 similar to the one in FIG. 6, but with five radial projections 10 which are distributed at regular intervals.

FIGS. 8 and 9 show thumb wheels 7 having, respectively, five and four radial projections 10, and which differ from those in the preceding figures because the seating areas 11 are made up of surfaces which are convex in a plane that is orthogonal to axis 6.

FIG. 10 shows a thumb wheel 7 similar to the one in FIG. 9, with four radial projections 10, but in which the radial distance between the point of one seating area 11 nearest to axis 6 and the point of one radial projection 10 furthest away from axis 6 has been reduced. In this case, this distance is 0.6 millimetres. The maximum radius of thumb wheel 7, in other words the radius centred in axis 6 and passing through the end of a projection 10, is 4.0 millimetres.

FIG. 11 shows a variant of thumb wheel 7 corresponding to a particular case within the framework of the invention, wherein the periphery 9 of thumb wheel 7 consists of a regular polygon, in this case a pentagon, with rounded apices. In this case, said seating areas 11 are made up of the central area of the flat surfaces of the pentagon, while said radial projections 10 are made up of each rounded apex together with the section nearest said apex of the two adjacent flat surfaces. Furthermore, without departing from the context of the invention, an embodiment can be envisaged wherein the apices are sharp edges, in other words, not rounded.

Finally, FIGS. 12, 13 and 14 show variants of thumb wheel 7 that have four, six and five radial projections 10, respectively. These variants have the particular characteristic that radial projections 10 are shaped like straight radial tabs with a rounded end, and seating areas 11 are made up of the surface of a circular disc centred in axis 6 and interrupted regularly by radial projections 10 that project to therefrom.

It is worth mentioning that in the lighter according to the invention, an adult user's finger always remains firmly anchored in one of the seating areas 11 defined between two radial projections 10, whereby it is ensured that the finger is gripped well irrespective of the local friction coefficient on periphery 9 of thumb wheels 7. This means the furrowing on periphery 9 can be omitted, thereby significantly reducing manufacturing costs. This solution, which has been adopted in all the embodiments shown in FIGS. 1 through 13, does not seek or provide a lighting resistance effect; instead its sole aim is to reduce the manufacturing costs of thumb wheels 7. As explained above, in the lighter according to the invention, lighting resistance is based on reducing the rotation angle of toothed wheel 5, which is achieved thanks to the presence of radial projections 10 on thumb wheels 7. Although in the preferred embodiments the furrowing on periphery 9 of thumb wheels 7 has been omitted, the initial gripping properties have not been significantly reduced with respect to conventional lighters, since radial projections 10 and seating areas 11 actually form finger gripping points.

An skilled person will understand that the embodiments of the invention described above are merely non-limiting examples with respect to which several variants could be envisaged without thus departing from the context of this invention. In particular, since the invention is characterised by the particular shape of thumb wheels 7, the characteristics of all the other elements of the lighter are irrelevant insofar as the invention is concerned, with the sole condition that radial projections 10 are free from contact with any other element of the lighter. Also, some embodiments can be envisaged wherein the lighter has one single thumb wheel 7, or more than two thumb wheels 7, providing that one of them has the shape characterising the invention. 

1.-11. (canceled)
 12. A pocket lighter with a child resistance mechanism, said lighter comprising a liquated gas reservoir, a combustion chamber, a valve connecting said liquated gas reservoir to said combustion chamber, a lever that activates said valve, a flint, a toothed wheel mounted in rotation around an axis and which rubs against said flint creating sparks in the direction of said combustion chamber, and at least one thumb wheel, coaxial with said axis and integral with said toothed wheel, suitable for being drawn in rotation by a user's finger; wherein said thumb wheel has on its periphery a plurality of radial projections, there being defined between each pair of said consecutive radial projections a seating area with respect to which said radial projections project in the radial direction, said radial projections being free from contact with any other element of the lighter, and the total number of said radial projections being less than or equal to ten and greater than or equal to three, said periphery of the thumb wheel being directly accessible to a user's finger.
 13. The pocket lighter according to claim 12, wherein there are two of said thumb wheels, arranged on both sides of said toothed wheel.
 14. The pocket lighter according to claim 13, wherein said two thumb wheels are arranged with their radial projections in phase.
 15. The pocket lighter according to claim 12, wherein there are six of said radial projections in total and they are distributed at regular intervals around a circumference centred in said axis.
 16. The pocket lighter according to claim 12, wherein there are five of said radial projections in total and they are distributed at regular intervals around a circumference centred in said axis.
 17. The pocket lighter according to claim 12, wherein there are four of said radial projections in total and they are distributed at regular intervals around a circumference centred in said axis.
 18. The pocket lighter according to claim 12, wherein said radial projections form, at the end thereof furthest away from said axis, a surface which is convex in a plane that is orthogonal to said axis, with a radius of curvature that is less than the radius from said axis to said end of radial projection.
 19. The pocket lighter according to claim 12, wherein said seating areas form a surface which is concave in a plane that is orthogonal to said axis.
 20. The pocket lighter according to claim 12, wherein the radial distance between the point of one seating area nearest said axis and the point of one radial projection furthest away from said axis is greater than or equal to four tenths of a millimetre.
 21. The pocket lighter according to claim 12, wherein the radial distance between the point of one seating area nearest said axis and the point of one radial projection furthest away from said axis is greater than or equal to seven tenths of a millimetre.
 22. A thumb wheel for supplying a child resistance effect to a lighter, said lighter comprising a liquated gas reservoir, a combustion chamber, a valve connecting said liquated gas reservoir to said combustion chamber, a lever that activates said valve, a flint and, a toothed wheel mounted in rotation around an axis and which rubs against said flint creating sparks in the direction of said combustion chamber; said thumb wheel being provided on its periphery with a plurality of radial projections, there being defined between each pair of said consecutive radial projections a seating area with respect to which said radial projections project in the radial direction; the total number of said radial projections being less than or equal to ten and greater than or equal to three; said thumb wheel being mounted on said lighter coaxially with said axis and integrally with said toothed wheel, so that: said thumb wheel is suitable for being drawn in rotation by a user's finger; said radial projections are free from contact with any other element of the lighter, and the periphery of said thumb wheel is directly accessible to a user's finger. 